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VLB video card POST behavior

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First post, by vstrakh

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I'm building a 486DX2-66 system, this is the first time I ever use/own a VLB video card (CL GD-5428), and there's one weird quirk I don't know how to interpret.

On a cold boot the system properly detects stuff and all, showing "energy star" logo, etc.
But when doing warm reboot with Ctrl-Alt-Del, or when exiting the BIOS without saving, or doing hard reset - the bios beeps error code saying video card is not detected, but then immediately something kicks in (I believe I can see video bios messages blinked shortly) and the bios continues booting with video ok, with all graphical bells and whistles.
Looks totally ok after that error beep, but I didn't test it any further (multi i/o, CF-IDE setup needed, etc).

Any ideas on what that behavior could mean?

The mobo is built on FOREX FRX46C512A chipset, has onboard 256KB of cache all soldered and cache config options are hardwired.
Looks exactly like this one: https://www.ultimateretro.net/en/motherboards/2512
The Award BIOS V4.50G shows "U-BOARD GREEN PC" name , and the id string is "07/11/94-FOREX-46C521A-2C4R3U01-00".
Initially the motherboard came with U5S-SUPER33 cpu overclocked to 40MHz, but I reverted all jumper settings to 33MHz and switched cpu type for 486DX2, the bios reports it as 486DX2-S at 66MHz.

Reply 1 of 2, by sirotkaslo

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I have a 486 with the pc chips m912 and it does something similar with the GD5434 vlb card. Every time it powers up (turn on or reset, doesn't matter) I get three bios beeps and then normal post. I'm using the Am486DX2-80 cpu so in my case it could be 40mhz fsb that's giving me issues since I also use a disk controller on vlb.

Reply 2 of 2, by vstrakh

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I must say it's very likely the issue is about VESA pins connectivity.
I get card not detected sometimes, or the colors get weird (I assume when palette is written to ramdac).
The rear part of ISA connector is pushing the card hard, and the mechanical sizes/tolerances are barely covering the shift. Pins lose the contacts unless the mother board is slightly bent from beneath.
I guess I'll sand off a tiny bit of the card's edge connector that gets pushed by ISA slot to reduce the shift in VESA part.

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